The Department of Justice has begun a broad criminal investigation into Americans who have worked with Russia’s state television networks, signaling an aggressive effort to combat the Kremlin’s influence operations leading up to the presidential election in November, according to American officials briefed on the inquiry.

This month, F.B.I. agents searched the homes of two prominent figures with connections to Russian state media: Scott Ritter, a former United Nations weapons inspector and critic of American foreign policy, and Dimitri K. Simes, an adviser to former President Donald J. Trump’s first presidential campaign in 2016. Prosecutors have not announced charges against either of the men.

More searches are expected soon, some of the officials said, speaking on the condition of anonymity to discuss investigations. Criminal charges are also possible, they said.

The investigation comes in the wake of the Biden administration’s official intelligence findings that Russia’s state news organizations, including the global news channel RT, are working with its intelligence agencies to sway elections around the world.

Those efforts include November’s contest between Mr. Trump and Vice President Kamala Harris. For a third time, according to the officials and public statements, the Kremlin’s propaganda apparatus has thrown itself behind Mr. Trump’s candidacy, creating online news outlets and fake videos to denigrate President Biden and, more recently, Ms. Harris.

The investigation so far has focused on potential violations of the economic sanctions imposed on Russia after its invasion of Ukraine and a law that requires the disclosure of lobbying efforts on behalf of foreign governments.